CELL & MOLEC BIO EXAM 1

Gregor Mendel

revealed that
heredity is the result of discrete units of
inheritance

Nettie Maria Stevens

An American geneticist, she discovered
sex chromosomes in mealworms which
would later be termed “X” and “Y”
chromosomes (1905)

Wilhelm Ludvig Johannsen

Danish scientist who coined the term
gene to refer to the unit or particle of
inheritance. (1903)

Archibald Garrod

Archibald Garrod (1905)
identifies alkaptonuria as
a heritable genetic
disease that follows
Mendel’s laws.
Alkaptonuria - “black
urine” - inborn error of
metabolism

Ernest Everett Just

An American embryologist, he was the first
to conceptualize epigenetics: the
environment contributes to how the
information in DNA becomes physical
characteristics of an organism

Thomas Hunt Morgan

An American geneticist,
he discovered that
certain mutations were
inherited together
(linked)

Frederick Griffith

Frederick Griffith was a British bacteriologist whose focus was the epidemiology and pathology of bacterial pneumonia.

Avery, McCarty, and McLeod

R-strain
could be transformed with
DNA extracts from dead S -
strain 

Alfred Hershey and Marsha Chase

Alfred Hershey and Marsha Chase
labeled bacteriophages with
radioactive elements

Erwin Chargaff

Nucleotides occur in predictable
ratios in living things

James Watson
- Francis Crick

Rosalind Franklin
- Maurice Wilkins

Discovery of the structure of DNA

Linus Pauling

Major contributions to quantum physics,
biophysics, and peace advocate.

What are the 6 elemental constituents of life

CHONPS: carbon, hydrogen, oxygen, nitrogen, phosphorus, & sulfur

What is the content % of Carbon in the cell and its relative electronegativity?

10% and ~2.2

What is the content % of Hydrogen in the cell and its relative electronegativity?

~63% and ~3.4 (high electronegativity)

What is the content % of Oxygen in the cell and its relative electronegativity?

~24% and ~3.5

What is the content % of Nitrogen in the cell and its relative electronegativity?

1.4% and ~3.0 (high electronegativity)

What is the content % of Phosphorus in the cell and its relative electronegativity?

0.2% and ~2.2

What is the content % of Sulfur in the cell and its relative electronegativity?

~0.01% and ~2.6

Properties of polar covalent bonds

Occur when atoms with different electronegativities share electrons unevenly, resulting in a molecule with partial positive and negative charges.

Properties of nonpolar covalent bonds

Occur when atoms with similar electronegativities share electrons evenly, resulting in a molecule with no partial charges.

What are the four maor noncovalent bonds/interactions that shape macromolecules?

Hydrogen bonds, ionic bonds, van der Waals forces, hydrophobic interactions.

How to hydrogen bonds arise?

They arise when a hydrogen atom covalently bonded to a highly electronegative atom, such as oxygen or nitrogen, experiences an attraction to another electronegative atom.

How to ionic bonds arise?

They arise when one atom donates an electron to another atom, resulting in the formation of positively and negatively charged ions that attract each other.

How to Van der Waals attractions arise?

They arise from transient dipoles that occur when electron distributions around atoms fluctuate, leading to weak attractions between nearby molecules or atoms. Together the are strong

How to hydrophobic interactions arise?

They arise when nonpolar molecules aggregate in aqueous environments to minimize their exposure to water, driven by the tendency of water to exclude nonpolar substances.

Hydrogen bond relative strength:

Stronger than Van der Waals interactions but weaker than ionic and covalent bonds.

Ionic bond relative strength:

Stronger than hydrogen bonds but weaker than covalent bonds.

Van der Waals attraction relative strength:

Weaker than hydrogen bonds and ionic bonds, but can be significant in large molecules.

Hydrophobic interaction relative strength:

Weaker than hydrogen bonds but can influence molecular structure significantly.

What are the four main categories of carbon-based molecules that make up the cell?

Sugars, Fatty acids, Amino acids, Nucleotides.

What macromolecule has the subunit of sugars?

Glycogen and Starch

What macromolecule has the subunit of fatty acids?

Membrane lipids and fats

What is it called when a molecule is partly hydrophobic and partly hydrophilic?

Amphipathic

What macromolecule has the subunit of amino acids?

Proteins

What macromolecule has the subunit of nucleotides?

DNA and RNA

Complex molecues are builth through the ________ of simple subunits and broken down through ________.

condensation and hydrolysis

How are complex macromolecules built through the condensation of simple subunits and broken down through hydrolysis?

Complex macromolecules are built through the process of condensation by joining simple subunits together, releasing water molecules as a byproduct. Conversely, they are broken down through hydrolysis, where water is used to break the bonds between the subunits.

What bond type links subunits in glycogen and starch?

glycosidic bonds

What bond type links subunits in membrane lipids and fat?

ester bonds

What bond type links subunits in proteins?

peptide bonds

What bond type links subunits in DNA and RNA?

phosphodiester bonds

What is the 1st Law of Thermodynamics?

Conservation of energy - energy cannot be created or destroyed, only change form.

What is the 2nd Law of Thermodynamics?

The degree of disorder in a system can only increase.

What is catabolism?

The metabolic process that breaks down complex molecules into simpler ones, releasing energy

What is anabolism?

The metabolic process that builds complex molecules from simpler ones, requiring energy

What are redox reactions?

chemical reactions involving the transfer of electrons, where oxidation is the loss of electrons and reduction is the gain of electrons

What is hydrogenation?

A chemical reaction where hydrogen is added to a molecule, often reducing double or triple bonds in organic compounds

What is dehydrogenation?

A chemical reaction that removes hydrogen from a molecule, often creating double or triple bonds

What is the role of enzymes in chemical reactions?

to act as biological catalysts in chemical reactions, speeding up reactions by lowering the activation energy without being consumed in the process

What is ∆G?

(Gibbs free energy change) measures the amount of energy available to do work in a chemical reaction.

What are coupled reactions?

two or more chemical reactions that occur together, where the energy released from one reaction (unfavorable) is used to drive another reaction (favorable). This allows cells to perform processes that require energy, like the synthesis of molecules.

What is indirect coupling?

Unfavorable reactions (those with a positive ΔG) can be made to proceed by removing reaction products as they are formed. This decreases the concentration of products, shifting the equilibrium toward product formation. By continuously removing the products, the reaction can be driven forward, helping it to reach completion despite its natural tendency to go in the opposite direction.

What are activated carrier molecules?

They store and transfer energy in cells. Examples include ATP (phosphate groups), NADH/NADPH (electrons), and Coenzyme A (acyl groups).

What is ATP?

adenosine triphosphate: a molecule that stores and transfers energy within cells

NADH vs. NADPH

NADH is used in cellular respiration to generate ATP, while NADPH provides reducing power for biosynthetic reactions like fatty acid and nucleotide synthesis.

NADH

NADH (nicotinamide adenine dinucleotide) is a molecule that carries electrons in cellular respiration, helping to produce ATP by transferring electrons to the electron transport chain

NADPH

NADPH (nicotinamide adenine dinucleotide phosphate) is a molecule that carries electrons and provides reducing power for biosynthetic processes, such as fatty acid and nucleotide synthesis

All amino acid molecules have the same backbone consisting of:

amine group, a-carbon with side chain, and carboxyl group

Proteins are composed of

amino acids

Proteins are composed of amino acids that are covalently linked with ______ into a ______.

peptide bonds and polypeptide

The polypeptide chain is directionally arranged from the _______ of the first amino acide to the ______ of the last amino acid.

amino group and carboxyl group

How do you determine if a side chain is polar?

To determine if a side chain is polar, you look at its ability to form hydrogen bonds, which is typically due to the presence of electronegative atoms like oxygen or nitrogen. Polar side chains often contain:

• Hydroxyl groups (-OH)

• Amino groups (-NH₂)

• Carbonyl groups (C=O)

• Sulfur-containing groups (like thiol -SH)

These groups are hydrophilic and interact well with water, making the side chain polar. Nonpolar side chains typically have hydrocarbon structures that don't form hydrogen bonds.

How do you determine if a side chain is charged?

To determine if a side chain is charged, you check if it contains a group that can gain or lose a proton (H⁺), which typically happens at specific pH levels. Charged side chains can be:

• Positively charged (basic): Side chains with amino groups (-NH₂, -NH₃⁺) that can accept a proton, such as in lysine, arginine, and histidine.

• Negatively charged (acidic): Side chains with carboxyl groups (-COOH, -COO⁻) that can lose a proton, such as in aspartic acid and glutamic acid.

These charged groups are hydrophilic and interact strongly with water.

How do you determine if a side chain is hydrophobic?

To determine if a side chain is hydrophobic, you look for a nonpolar structure, typically made up of hydrocarbons (carbon and hydrogen). These side chains do not form hydrogen bonds and are repelled by water, making them hydrophobic.

What is the notable properties of the amino acid Glycine?

jsut has an H as a side chain making this amino acid a very flexilbe component of a protein

What is the notable properties of the amino acid Proline?

the side chain of this amino acid forms a ring with the N of the amine group which constrains the rotation of this amino acid - adds rigidity to protein

What is the notable properties of the amino acid Cysteine?

covalent disulfide bonds can form between the sulfur atoms of these amino acids - stabilizes tertiary and quaternary structure of proteins - primarily found in extracellular proteins

What is the notable properties of the amino acids Serine, Threonine, and Tyrosine?

have -OH groups that can be phosphorylated to change the activity of the protein and glycosylated where the sugars are covalently bonded to change structure and function

What is the notable properties of the amino acids Asparagine and Arginine?

have -NH₂ groups that can be glycosylated where the sugars are covalently bonded to change structure and function

Proteins fold into a very specific conformation through noncovalent bonds and interactions including:

hydrogen bonding, ionic bonding, Van der Waals forces, and gydrophobic interactions

What disrupt the noncovalent interactions in proteins?

denaturing agents like urea

In the cell, what aid in folding proteins to find the most energetically favorable conformation and/or prevent aggregation with other proteins?

molecular chaperons

What are four levels of organization in proteins?

primary, secondary, tertiary, and quaternary.

What makes up the primary level of organization in proteins?

linear sequence of amino acids

What makes up the secondary level of organization in proteins?

a-helices and ß-sheets that form for the hydrogen bonding between N-H and C=O of the peptide backbone

What makes up the tertiary level of organization in proteins?

the overall conformation of a single polypeptide chain

What makes up the quaternary level of organization in proteins?

the combined structure of multiple separate polypeptide chains that combine into a multisubunit protein